False PT/INR Results May Appear for Some Patients

Alere has issued a voluntary correction to users of the Alere INRatio and INRatio 2 PT/INR Monitor system of certain medical conditions that should not be tested with the system (INRatio Monitor INRatio 2 Monitor and INRatio Test Strips).

Certain medical conditions may result in an INR result that is clinically significantly lower than a result using a laboratory method (reference INR). The system should not be used in patients with:

  • Anemia of any type with hematocrit <30%
  • Any conditions associated with elevated fibrinogen levels including:
    • Acute inflammatory conditions (eg, acute viral or bacterial infections such as pneumonia or influenza)
    • Chronic inflammatory conditions (eg, rheumatoid arthritis, Crohn's disease, ulcerative colitis, infectious liver diseases such as hepatitis, or inflammatory kidney diseases such as diabetic nephropathy and glomerulonephritis).
    • Severe infection (eg, sepsis)
    • Chronically elevated fibrinogen for any reason
    • Hospitalized or advanced stage cancer or end stage renal disease patients requiring hemodialysis.
  • Any bleeding or unusual bruising, clinically observed or reported by the patient. 

RELATED: INR Variability Predicts Warfarin Adverse Effects

In these cases, patients should have their INR and warfarin therapy monitored by a laboratory INR method. To obtain the most accurate results, healthcare professionals and patient self-testers are also recommended to do the following:

  • Patients should have periodic verification of their INR using a laboratory INR method.
  • If a significantly discrepant low result on the INRatio and INRatio 2 monitor system vs. plasma-based laboratory INR method occurs, patient should immediately be transitioned to an alternative method for monitoring their INR and warfarin therapy.
  • Significant discrepancy in INR results may delay decision to reverse a supratherapeutic INR level following the established guidelines for monitoring warfarin therapy.
    • Take caution when the incorrect INR result is within the therapeutic range but the actual value is supratherapeutic, (eg, when the actual INR value is 6 or greater).
  • Patients should be tested to confirm that their hematocrit falls within the 30–55% range.

The device concerns have been reported to the Food and Drug Administration, and Alere is investigating into these events.

For more information call (877) 929-2579 or visit INR-Care.com.


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